SciCombinator

Discover the most talked about and latest scientific content & concepts.

280

To compare the effects of a programme of load management education plus exercise, corticosteroid injection use, and no treatment on pain and global improvement in individuals with gluteal tendinopathy.

274

The Middle to Later Stone Age transition in Africa has been debated as a significant shift in human technological, cultural, and cognitive evolution. However, the majority of research on this transition is currently focused on southern Africa due to a lack of long-term, stratified sites across much of the African continent. Here, we report a 78,000-year-long archeological record from Panga ya Saidi, a cave in the humid coastal forest of Kenya. Following a shift in toolkits ~67,000 years ago, novel symbolic and technological behaviors assemble in a non-unilinear manner. Against a backdrop of a persistent tropical forest-grassland ecotone, localized innovations better characterize the Late Pleistocene of this part of East Africa than alternative emphases on dramatic revolutions or migrations.

262

Organic semiconductors enable the fabrication of a range of lightweight and mechanically flexible optoelectronic devices. Most organic semiconductor lasers, however, have remained rigid until now, predominantly due to the need for a support substrate. Here, we use a simple fabrication process to make membrane-based, substrate-less and extremely thin (<500 nm) organic distributed feedback lasers that offer ultralow-weight (m/A<0.5 gm-2) and excellent mechanical flexibility. We show operation of the lasers as free-standing membranes and transfer them onto other substrates, e.g. a banknote, where the unique lasing spectrum is readily read out and used as security feature. The pump thresholds and emission intensity of our membrane lasers are well within the permissible exposures for ocular safety and we demonstrate integration on contact lenses as wearable security tags.

262

Predator-prey interactions revealed by vertebrate trace fossils are extremely rare. We present footprint evidence from White Sands National Monument in New Mexico for the association of sloth and human trackways. Geologically, the sloth and human trackways were made contemporaneously, and the sloth trackways show evidence of evasion and defensive behavior when associated with human tracks. Behavioral inferences from these trackways indicate prey selection and suggest that humans were harassing, stalking, and/or hunting the now-extinct giant ground sloth in the terminal Pleistocene.

258

Traditional paddy rice farmers had to share labor and coordinate irrigation in a way that most wheat farmers did not. We observed people in everyday life to test whether these agricultural legacies gave rice-farming southern China a more interdependent culture and wheat-farming northern China a more independent culture. In Study 1, we counted 8964 people sitting in cafes in six cities and found that people in northern China were more likely to be sitting alone. In Study 2, we moved chairs together in Starbucks across the country so that they were partially blocking the aisle (n = 678). People in northern China were more likely to move the chair out of the way, which is consistent with findings that people in individualistic cultures are more likely to try to control the environment. People in southern China were more likely to adjust the self to the environment by squeezing through the chairs. Even in China’s most modern cities, rice-wheat differences live on in everyday life.

247

Ground and satellite observations show that air pollution regulations in the United States (US) have resulted in substantial reductions in emissions and corresponding improvements in air quality over the last several decades. However, large uncertainties remain in evaluating how recent regulations affect different emission sectors and pollutant trends. Here we show a significant slowdown in decreasing US emissions of nitrogen oxides (NO x ) and carbon monoxide (CO) for 2011-2015 using satellite and surface measurements. This observed slowdown in emission reductions is significantly different from the trend expected using US Environmental Protection Agency (EPA) bottom-up inventories and impedes compliance with local and federal agency air-quality goals. We find that the difference between observations and EPA’s NO x emission estimates could be explained by: (i) growing relative contributions of industrial, area, and off-road sources, (ii) decreasing relative contributions of on-road gasoline, and (iii) slower than expected decreases in on-road diesel emissions.

241

Vectorborne diseases are major causes of death and illness worldwide. In the United States, the most common vectorborne pathogens are transmitted by ticks or mosquitoes, including those causing Lyme disease; Rocky Mountain spotted fever; and West Nile, dengue, and Zika virus diseases. This report examines trends in occurrence of nationally reportable vectorborne diseases during 2004-2016.

240

Aerosol composition measurements made in an indoor classroom indicate the uptake of thirdhand smoke (THS) species to indoor particles, a novel exposure route for THS to humans indoors. Chemical speciation of the organic aerosol fraction using mass spectrometric data and factor analysis identified a reduced nitrogen component, predominantly found in the indoor environment, contributing 29% of the indoor submicron aerosol mass. We identify this factor as THS compounds partitioning from interior surfaces to gas phase and then aerosol phase. Partitioning of THS vapors to aerosols requires an aqueous phase for reactive uptake of the reduced nitrogen species (RdNS), leading to seasonal differences in THS concentration indoors. RdNS protonate under the acidic conditions expected for indoor aerosols of outdoor origin. Controlled laboratory measurements performed using cigarette smoke deposited into a Pyrex vessel showed a similar partitioning behavior to aerosol of outdoor origin and mass spectral features comparable to the measured indoor THS factor after 1 week of residence time in the closed vessel. This study reports a new, potentially large THS exposure route from partitioning of surface volatile organic compounds into the aerosol phase and subsequent dispersion in a mechanically ventilated building.

231

By force of nature, every bit of spoken language is produced at a particular speed. However, this speed is not constant-speakers regularly speed up and slow down. Variation in speech rate is influenced by a complex combination of factors, including the frequency and predictability of words, their information status, and their position within an utterance. Here, we use speech rate as an index of word-planning effort and focus on the time window during which speakers prepare the production of words from the two major lexical classes, nouns and verbs. We show that, when naturalistic speech is sampled from languages all over the world, there is a robust cross-linguistic tendency for slower speech before nouns compared with verbs, both in terms of slower articulation and more pauses. We attribute this slowdown effect to the increased amount of planning that nouns require compared with verbs. Unlike verbs, nouns can typically only be used when they represent new or unexpected information; otherwise, they have to be replaced by pronouns or be omitted. These conditions on noun use appear to outweigh potential advantages stemming from differences in internal complexity between nouns and verbs. Our findings suggest that, beneath the staggering diversity of grammatical structures and cultural settings, there are robust universals of language processing that are intimately tied to how speakers manage referential information when they communicate with one another.

230

A taxonomic description of all castes of Colobopsis explodens Laciny & Zettel, sp. n. from Borneo, Thailand, and Malaysia is provided, which serves as a model species for biological studies on “exploding ants” in Southeast Asia. The new species is a member of the Colobopsis cylindrica (COCY) group and falls into a species complex that has been repeatedly summarized under the name Colobopsis saundersi (Emery, 1889) (formerly Camponotus saundersi). The COCY species group is known under its vernacular name “exploding ants” for a unique behaviour: during territorial combat, workers of some species sacrifice themselves by rupturing their gaster and releasing sticky and irritant contents of their hypertrophied mandibular gland reservoirs to kill or repel rivals. This study includes first illustrations and morphometric characterizations of males of the COCY group: Colobopsis explodens Laciny & Zettel, sp. n. and Colobopsis badia (Smith, 1857). Characters of male genitalia and external morphology are compared with other selected taxa of Camponotini. Preliminary notes on the biology of C. explodens Laciny & Zettel, sp. n. are provided. To fix the species identity of the closely related C. badia, a lectotype from Singapore is designated. The following taxonomic changes within the C. saundersi complex are proposed: Colobopsis solenobia (Menozzi, 1926), syn. n. and Colobopsis trieterica (Menozzi, 1926), syn. n. are synonymized with Colobopsis corallina Roger, 1863, a common endemic species of the Philippines. Colobopsis saginata Stitz, 1925, stat. n., hitherto a subspecies of C. badia, is raised to species level.